Endless track for half-track tractors



May 31, 1938. l H. w. ALDEN 2,118,961

ENDLESS 'TRACK FOR HALF-TRACK TRACTORS Filed March 20, 1934 INVENTOR 5Jf4 Heferf W ,4l/den ATTORNEY Patented May' 31, 19384 UN1TED sTATEsENDLESS TRACK FOR HALF-TRACK TRACTOR'S Herbert W. Alden, Detroit, Mich.,assignor to The Timken-Detroit Axle Company, Detroit, Mich.,

a corporation of Ohio Application March zo,

9 Claims.

This invention relates to endless tracks in gen- Veral and moreparticularly to endless tracks adapted for use on half-track tractors.For the purpose of this invention, what are conventionally known assix-wheel vehicles, that is, trucks having a conventional single axle atthe front and dual axles'at the rear, having four road wheels, thelatter having endless tracks associated therewith, will be termedhalf-track 10 tractors.

Half-track tractors have become quite popular due to their increasedexibility over the full trackitractors. 'Some users of half-tracktractors iin'd it desirable to have interchangeability on their rearwheels; that is, where road conditions are good, conventional wheels andtires are used and where road conditions are bad, an endless track isused. For -such usage, and even where the track constitutes thepermanent traction mechanism, it is not necessary or desirable to havethe wide, heavy and cumbersome endless track of the full track tractor.A track of ex treme lightness, yet having suflicient strength, isdesired. It is further desirableand even more so in the conversionjobs-that the track be so constructed that it may be easily disconnectedfor removal from the vehicle.

The endless tracks that have been heretofore proposed have beenunsuitable flor operation in half-track tractors or other installationswhere fairly high speed, quietness of operation and flexibility areprime considerations, because their relatively massive constructionmakes it impracticable to operate them at high speed and their inherentdesign renders them noisy in operation,

even at fairly low speeds. In such prior mechanisms, the track or treadmembers are constructed of metal, with the result that when they passover the driving sprockets and load supporting rollers they set upanexcessive noise. Moreover, when such track constructions are operated onpaved roads or streets, the metallic treads are extremely noisy inoperation.

I am aware that endless tracks having rubber treads have been heretoforeproposed, but such track constructions have never gone into commercialuse for the reason that the rubber treads stretch, and distort to such adegree when placed under load, that the links do not properly ride uponthe sprockets. Such prior constructions were also defective because therubber treads would not only getA out of proper alignment but wouldoften tear loose from the links after they had been in use for only ashort period. of time.

Another disadvantage inherent in such @prior 1934, serial No. naar.c

(ci. sos-1o) track constructions resides in the fact that althoughtension members were incorporated in their rubber treads for taking thepull exerted by the sprockets, the rubber was merely loosely moldedabout the reenforcing means, with the result 5 that the twisting actionof the track when in operation would cause the reenforcing means, andsometimes the link, pins orbushings, to pull free from the rubber, andthereby render the track: useless. Such prior constructions in additionto 10 possessing the' disadvantages just discussed, are also extremelycostly to manufacture.

It is accordingly a principal object of my inf vention to devise anendless track which is light and flexible, but which `is neverthelessdurable and which may be cheaply manufactured.

It is another major object of my invention to devise a novel endlesstrack which is simple in design, involves no slidably moving parts, andisalmost silent in operation.

It is another important object of my invention to provide an endlestrack o1' the character having a. plurality of non-metallic treadmembers, each of which has a face constituting a bearing surface, and aload supporting surface, with means 25 for? efficiently reenforcing itagainst harmful stretching in operation.

Another object is to devise a novel endless track which may bedisconnected, for removal from the A vehicle on which itis installed,with a minimum 30 of diiiiculty.

Another object of my invention is to so design the parts of an endlesstrack that they may be readily assembled and disassembled.

It is a further object of this invention to pro- 35 vide an endlesstrack, whose tread portions are constructed of rubber, with a drivingconnection molded therein that emciently maintains proper alignment ofthe track at all times.

It is a still further object of this invention to 40 devise a novelsprocket and pulley assembly for an endless track construction.

Another object is to devise a novel sprocket and pulley organization foran endless track construction, which may be readily disassembled to 45permit removal of the track, and/or the substitution of load-supporting.wheels therefor.

Further objects of my invention will appear as the detailed descriptionthereof proceeds in connection with the annexed drawing and from the 50appended claims.

In the drawing: Figure 1 is an elevational view of a portion of thetrack of the present invention, in position on a driving sprocket.'

Figure 2 is a plan view, in partial section of the track shown in Figure1, looking upwardly in that figure.

Figure 3 isa sectional view through the outer end of a driving axleshowing the invention applied thereto, and,

Figure 4 is a sectional view of one of thetread members and is takenalong the line 4-4 of Figure 2.

Referring now to the drawing wherein like reference numerals refer tolike parts wherever they may occur,v and with particular reference toFigure 2, the numeral I represents an outer member or tread which ispreferably made of molded rubber, but which can be made of any suitableresilient or fibrous material, and it is essentially rectangular insection, having at its upper surface two lateral pads or feet 3 with adepression 4 therebetween.

Molded or cast within member I are two spaced members 6, which areconstructed of rather thin metal and have a pair of apertures formedtherein. Extending through the apertures in members 6, are a pair ofcylindrical sleeves 8. Members 6 are preferably welded or otherwisesecured in spaced relationship on cylinders or sleeves 8 and this ispreferably e'ected before they are molded or cast within member I. Asleeve of rubber or other resilient material I0 is disposed withinsleeve 8,` and a second metallic sleeve I2, which is tapered throughoutits length on its inside diameter, is disposed within rubber edrelatively to each other.. The term mass tension is used to describe thecondition of the rubber when bushing I0 is so dimensioned that the partsfit tightly and the rubber flows or is distorted when they are forcedinto place. Although I prefer to employ a rubber joint in myconstruction, sleeve 8 may be made thicker and be journalled directlyupon sleeve I2 and a satisfactorily operating device obtained.

Each tread assembly consists of a pair of tread members, and they aredisposed side by side as seen in Figure 2, and extending through thetapered portions of sleeves I2, and removably secured therein by nutsI5,.a.re pi ns I6 which are symmetrical about their vertical centerlines, that is, they have two such tapered portions, one at each endjoined by straight portions I1 at their centers. Straight portions I1 ofpins I6 are adapted to be press-fitted into apertures provided thereforin links 20. Links 20 consist essentially of two cylindrical portions2I-which have the before mentioned apertures therein-which are joined attheir ends bytriangular web portions 22, and which contain holes 23 forthe purpose of reducing their weight. The openings 24 defined by the twocylindrical portions 2| and the web portions 22 of links 20 form femaledriving notches for teeth 26 4of a driving sprocket 30. As has beenindicated when sleeves I2 are drawn up on the tapered portion of pins I6 by tightening nuts I5, a frictional bond is established between theparts, and although nuts l5 may be turned home in any desired manner, IpreferablyV assemble the parts and tighten nuts I5 when the treads aredisposed flat and links 20 are symmetrically disposed with respectthereto, so that the rubber bushings will constantly tend to cause thetrack to assume a flat or straight configuration.

Referring now to Figure 3, sprocket 30 is a substantially flat disk andhas teeth 26 at its outer periphery, and suitable apertures forattaching it to a hub member, and suitable at surfaces, annular pilotshoulders and bolt holes for attaching supporting wheels 40. A pair ofsupporting wheels 40 are associated with sprocket 30 and are ofidentical construction, and each has a cylindrical portion 42 whoseoutside diameter is equal to, or just slightly less than the di ameterformed by the inner surfaces of treads when the latter are in positionon the wheels. Cylindrical portions 42 are supported by walls 44,leading therefrom to flanges which register with the surfaces providedtherefor on sprocket 38. Wheels'40 are reinforced by means of a seriesof ribs 46, which extend radially between the attaching bolts 41 fromthe outermost por'- tion ofthe cylindrical surfaces 42 to the inner edgeof the wheels. Cylindrical or drum portions 42 of wheels 40 are adaptedto ride directly upon the inner surfaces of treads I and thereby preventany undue amount of bending of pins I5, and insulate the wheels from themetal parts of the track insofar as load supporting functions thereofare concerned.

' With further reference to Figure 3, it will be noted that the outerend of a conventional driving axle, is illustrated, and it consistsessentially of a housingn nose 50 through which extends a sle'eve 5I.Bearings 52 are supported on sleeve 50 and they are suitably secured inplace thereon by a locking assembly 53. A shaft 54 extends throughsleeve 5I, and to its flanged end is secured a hub member 55, which isin turn supported on bearings 52. A wheel stud 56 is inserted throughthe driving flange of hub 55 and by means of nuts, removably secures abrake drum 51 on one side thereof, and sprocket 38 on the other. Anyconventional type of brake mechanism (not shown) may be used and mountedon a backing plate 58, which is shown as being riveted to housing nose58.

` The assembly of the above-described. endless track is very simple.Pins I6 are rst preferably press-fitted into links 20 to the desiredposition, then treads I, which as before mentioned, are made as a unit,are merely assembled upon the tapered portions of two a acent pins oflinks which have been placed end to end. Nuts I5 are then threaded intoplace and tightened so that the respective treads are drawn rmly inplace upon the taperediportions of pins I8.

If desirable, the sprockets and endlesstrack L may be assembled as aunit and then bolted to the driving members, or the sprockets may firstbe -assembled and the endless track put on last The operation of mydevice is as follows. When the vehicle is stationary or moving, the loadis .traction conditions.

face and the drum portion 42 of wheels 40, and

also any ancillary, load-supporting rollers. In this connection, it isto be observed that the inwardly extending portions of links 20 serve asguiding elements to prevent lateral displacement from wheels 40 or fromany ancillary load-supporting rollers that may be used in the tractor.construction. The load supporting rollers are disposed between thewheels and ride upon the track, and in a half-track tractor they onlytake. a portion of the load, whereas in a full tractor they usually takeall of the load. u

When rotative efforts are applied to shaft 54, they are transmittedthrough hub 55 to sprocket 30 and teeth 26 of the latter transmitsdriving forces to links 20. The pull imparted to links 2U by teeth 26 istransmitted to treads I through pins I6 and rubber bushings I0. Thetractive forces are transmitted through treads I by way of members 6,and as the latter are only subjected to tensional forces, they mayaccordingly be thin. In view of the fact that the engagement of treads Iwith wheels 40 presents a comparatively high coeicient of friction, asubstantial portion of the tractive effort is transmitted between thetwo in this manner.

It should be observed that as pins I6 are pressiitted into links 20, andas pins I6 are connected to treads I through resilient joints, nolubrication whatever is required for my track construction as no slidingmovement is present in the parts.

Although I have illustrated my track construction as being applied to ahalf-track tractor, it is to be understood that it may be used in anyother type of tractor without departing from the spirit of myinvention.l

Although I prefer to secure members to sleeves 8, it is to be understoodthat they may be merely loosely or frictionally fitted upon bushings 8,and the rubber of treads I relied upon to maintain them in properassembled position if vdesired without departing from the spirit of myinvention.

.It is observed that links 20 constitute the sole means of securing thetread units together, and while I prefer to use this construction, as itrenders the track exible and free from tendencies to clog up with soil,it is to be understood that if desired, link members may be employed toconnect the outer ends of pins I6 Without sacrificing the advantages ofmy resilient tread construction.

The invention may be embodied in other specie forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the

What is claimed and desired to be secured by United States LettersPatent is:

1. In an endless track construction in sub-combination, a tread elementadapted to form a part of an articulated track, comprising a pair ofparallelly disposed, longitudinally spaced sleeve members; means forconnecting said sleeve mem.-

bers together in spaced relationship and operable to prevent them frommoving away from each other; and a body of resilient materialsurrounding'the outer cylindrical surfaces of said sleeve members andcompletely enveloping said means,

` 2. The track construction described in claim 1, wherein said means isalso operable to restrain movement of said members toward each other.

3. The track construction described in claim. 1, wherein said means isoperable to restrain said sleeve members against .relative rotationalmovements about their axes.

4. The track construction described in claim 1, wherein said meanscomprises at least one' tensional element disposed between said sleevemembers and disposed in engagement with at least a portion of theirouter cylindrical surfaces.

5. The track construction described in claim 1, together with a secondpair of sleeve members disposed within said rst-named sleeve members andspaced therefrom by a body of rubber and frictionally secured thereto.

6. In an endless track construction, in subcombination, a resilienttread element, comprising a pair of parallelly disposed, longitudinallyspaced sleeve members; a relatively thin metallic element disposednormal to the axes of said sleeve members and having a pair of aperturesprovided therein, said sleeve members extending through said aperturesand having their outer surfaces disposed in engagement with the walls ofsaid apertures; and a body of resilient material surrounding the outercylindrical surfaces of said sleeve members and completely envelopingsaid metallic element.

'7. "I'he track construction described in claim 6, wherein said metallicelement is secured to said sleeve members to thereby prevent relativerotation thereof.

8. The track construction described in claim 6, together with a secondpair of sleeve members disposed within said rst-named sleeve membersvand having the outer walls thereof spaced from the latter by a body ofrubber disposed between them and frictionally secured thereto. 9. In anendless track construction, in subcombination, a tread member having apair of parallel spaced openings therein; a bushing disposed in eachopening, a rubber sleeve disposed in each bushing; a metallic sleeve,having a tapered inner surface, disposed in each rubber sleeve, and atleast one tension member embedded in said tread member and connected atits ends to said bushings, for preventing relative translationalmovement of the latter.

HERBERT W. ALDEN.

